US20050284670A1 - Weighing apparatus with roberval mechanism - Google Patents
Weighing apparatus with roberval mechanism Download PDFInfo
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- US20050284670A1 US20050284670A1 US10/875,370 US87537004A US2005284670A1 US 20050284670 A1 US20050284670 A1 US 20050284670A1 US 87537004 A US87537004 A US 87537004A US 2005284670 A1 US2005284670 A1 US 2005284670A1
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- load
- receiving portion
- roberval mechanism
- lever
- converting unit
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01G—WEIGHING
- G01G3/00—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances
- G01G3/12—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing
- G01G3/14—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing measuring variations of electrical resistance
- G01G3/1402—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
- G01G3/1412—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports the supports being parallelogram shaped
Definitions
- the present invention relates to a weighing apparatus comprising a Roberval mechanism including a base portion, a load receiving portion receiving a load to be measured and a pair of parallel link portions provided between the base portion and the load receiving portion via flexures, a load converting section including at least one lever having one end operationally coupled with said load receiving portion of the Roberval mechanism, and a load sensor operationally coupled with the other end of said lever, wherein the load applied to the load receiving portion of the Roberval mechanism is enlarged or reduced by the lever of the load converting section and a thus enlarged or reduced load is applied to the load sensor.
- the load converting section including a lever for reducing a load to be applied to the load sensor is provided within the Roberval mechanism.
- a freedom in designing the load converting section is limited.
- the load converting section includes only one lever having a relatively small length, a sufficiently large ratio for enlarging or reducing a load could not be attained.
- the present invention has for object to provide a novel and useful weighing apparatus of a kind mentioned in the preamble, in which the above mentioned drawbacks of the known weighing apparatuses can be effectively removed by providing a load converting section as a separate unit from a Roberval mechanism, and a sufficiently high load enlarging or reducing ratio can be attained while the weighing apparatus can be small and compact.
- a weighing apparatus for measuring a weight of an article comprising:
- said load converting section includes a first load converting unit having a plurality of levers coupled with each other in series, and a second load converting unit operationally coupled with the last lever of said first load converting unit, wherein said first load converting unit is provided in a plane perpendicular to the plane of the Roberval mechanism and said second load sensor is provided in a plane parallel to the plane of the Roberval mechanism.
- the second load converting unit may be formed as a Roberval mechanism and the load sensor unit may include a lever whose one end is operationally coupled with a load receiving portion of the Roberval mechanism of the second load converting unit, the other end of said lever of the load sensor unit being coupled with the load sensor.
- FIG. 1 is a perspective view showing an embodiment of the weighing apparatus according to the invention
- FIG. 2 is an exploded perspective view of the weighing apparatus
- FIG. 3 is a front view of a first load converting unit
- FIG. 4 is a front view of a second load converting unit
- FIG. 5 is a front view showing a load sensor unit.
- FIG. 1 is a perspective view illustrating an embodiment of the weighing apparatus according to the present invention and FIG. 2 is an exploded perspective view thereof.
- the weighing apparatus comprises a Roberval mechanism 1 secured to a supporting member 2 .
- the Roberval mechanism 1 is manufactured by cutting a single metal block into a given configuration.
- the Roberval mechanism 1 includes a base portion 3 , a load receiving portion 4 , upper and lower parallel link portions 5 ad 6 , and four flexures 7 , two of the four flexures being provided between the base portion 3 and the parallel link portions 5 and 6 and the remaining two flexures being provided between the load receiving portion 4 and the parallel link portions 5 and 6 .
- the Roberval mechanism 1 further comprises a fixing portion 3 a which extends from the base portion 3 inwardly toward the load receiving portion 4 .
- a first load converting unit 10 such that the first load converting unit 10 extends in a plane which is perpendicular to a plane in which the Roberval mechanism 1 extends.
- a second load converting unit 30 which extends in a plane which is perpendicular to the plane of the first load converting unit 10 and is in parallel with the plane of the Roberval mechanism 1 .
- a load sensor unit 50 including a tuning-fork type vibrating element.
- a base portion 11 of the first load converting unit 10 is secured to the fixing portion 3 a of the Roberval mechanism by means of lower bolts 9 a shown in FIG. 2 .
- the first load converting unit 10 is formed by piercing a metal block to have a number of cut-out portions and several levers.
- the fixing portion of the Roberval mechanism 1 has formed therein a projection extending toward the load receiving portion 4 and the above mentioned bolts 9 a are secured to this projection.
- the first load converting unit 10 includes a load receiving portion 12 which is coupled with the load receiving portion 4 of the Roberval mechanism 1 by means of upper bolts 9 b shown in FIG. 2 .
- the load receiving portion 4 of the Roberval mechanism 1 includes a projection 4 a extending toward the fixing portion 3 a and through holes. Screw holes are formed on a top surface of the load receiving portion 12 of the first load converting unit 10 and the bolts 9 b are screwed into these screw holes through the through holes formed in the projection 4 a to couple the load receiving portion 12 of the first load converting unit 10 to the load converting portion 4 of the Roberval mechanism 1 . As illustrated in FIG.
- the first load converting unit 10 further includes a first lever 14 whose one end is coupled with the base portion 11 via a flexure 13 serving as a fulcrum point P 1-1 .
- a middle portion of the first lever 14 is coupled with the load receiving portion 12 via a connecting portion 15 such that said middle portion serves as a power point P 1-2 .
- the other end of the first lever 14 serving as a point of action P 1-3 is coupled with one end of a second lever 19 by means of a flexure 16 , a connecting portion 17 and a flexure 18 .
- This end of the second lever 19 serves as a power point P 2-2 .
- the second lever 19 is supported by the base portion 11 by means of a flexure 20 serving as a fulcrum point P 21- .
- the other end of the second lever 19 is coupled with an upper end of a vertically extending connecting portion 22 via a flexure 21 serving as a point of action P 2-3 .
- a lower end of the connecting portion 22 is coupled with one end of a third lever 24 by means of a flexure 23 serving as a power point P 3-2 .
- the third lever 24 is connected to the base portion 11 via a flexure 25 serving as a fulcrum point P 3-1 , and the other end of the third lever 24 is coupled with a substantially circular connecting portion via a flexure 26 serving as a point of action P 3-3 , a connecting portion 27 and a flexure 28 .
- the base portion 11 , load receiving portion 12 , first to third levers 14 , 19 , 24 have a thickness equal to a thickness of the metal block from which the first load converting unit 10 is formed, but some of the flexures 13 , 16 , 18 , 20 , 21 , 23 , 25 , 26 , 28 have a thickness smaller than a thickness of the metal plate.
- FIG. 4 is a front view showing the second load converting unit 30 .
- the second load converting unit 30 is also formed by piecing a single metal block to constitute a Roberval mechanism including a base portion 31 , a load receiving portion 32 , parallel link portions 33 , 34 and four flexures 35 . As illustrated in FIG. 2 , each of the flexures 36 has formed therein a through hole 36 to reduce its effective thickness.
- the base portion 31 of the second load converting unit 30 is secured to a side wall of the fitting portion 3 a of the Roberval mechanism 1 by means of bolts 37 and a seat 3 b secured to the side wall of the fitting portion 3 a and having formed therein screw holes.
- On a front wall of the load receiving portion 32 of the second load converting unit 30 is provided a seat 32 a having a screw hole formed therein, and the connecting portion 29 of the first load converting unit 10 is secured to the seat 32 a by means of a bolt 38 .
- the second load converting unit 30 further comprises a sensor fitting portion 31 a to extend from the base portion 31 toward the load receiving portion 32 in a space formed between the upper and lower parallel link portions 33 and 34 .
- a seat 31 b having a screw hole formed therein and a screw hole 31 c into which a positioning pin 62 is screwed for positioning the sensor unit 50 .
- a seat 32 b On a side wall of the load receiving portion 32 of the second load converting unit 30 , is secured a seat 32 b having a screw hole formed therein for securing a load receiving portion of the load sensor unit 50 as will be explained later.
- a weight receiving box 40 is secured to the load receiving portion 32 of the second load converting unit 30 by means of bolts 41 .
- FIG. 5 is a front view of the load sensor unit 50 .
- the load sensor unit 50 is formed by piecing a relatively thin metal plate.
- the load sensor unit 50 includes a base portion 51 and a load receiving portion 52 .
- the base portion 51 is secured to the sensor fitting portion 31 a of the second load converting unit 30 by screwing a bolt 60 into the screw hole formed in the seat 31 b
- the load receiving portion 52 is secured to the load receiving portion 32 of the second load converting unit 30 by screwing a bolt 61 into the screw hole formed in the seat 32 b
- the base portion 51 of the load sensor unit 50 has formed therein a cut-out portion 51 b through which the positioning pin 62 extends from the side wall of the sensor fitting portion 31 a of the second load converting unit 30 to position the load sensor unit 50 .
- the load receiving portion 52 of the load sensor unit 50 is coupled with one end of a lever 55 by means of connecting portion 53 and a flexure 54 which serves as a power point P 4-2 .
- the lever 55 is supported by the base portion 51 by means of a flexure 56 serving as a fulcrum point P 4-1 , and the other end of the lever 55 is coupled with an upper end of a tuning fork 58 via a flexure 57 serving as a point of action P 4-3 .
- a lower end of the tuning fork 58 is coupled with the base portion 51 by means of a flexure 59 .
- the article Upon measuring a weight of an article, the article is placed on an article receiving pan (not shown in the drawings) secured to the load receiving portion 4 of the Roberval mechanism 1 , and then a load W is applied to the load receiving portion 4 and the load receiving portion descends. Since the load receiving portion 4 is constructed in the Roberval mechanism 1 , even though the load receiving portion 4 moves downward, the parallelogram formed by the base portion 3 , load receiving portion 4 and parallel link portions 5 , 6 is maintained.
- the load W applied to the load receiving portion 4 of the Roberval mechanism 1 is transferred to the load receiving portion 12 of the first load converting unit 10 and is further transferred to the power point P 1-2 of the first lever 14 .
- the load W is reduced to a value which is proportional to a ratio of a distance D 1 between the fulcrum point P 1-1 , and the power point P 1-2 and a distance D 2 between the fulcrum point P 1-2 and the point of action P 1-3 .
- the distance D 2 is longer than the distance D 1 by about three times, and therefore the load W is reduced to a third thereof.
- the thus reduced load is transferred to the power point P 2-2 of the second lever 19 via the connecting portion 17 .
- the load is further reduced by the lever 19 to a value proportional to a ratio of a distance between the fulcrum point P 2-1 and the power point P 2-2 and a distance between the fulcrum point P 2-1 and the point of action P 2-3 .
- the reduced load is further transferred via the connecting portion 22 to the third lever 24 .
- the load is further reduced to a value which is proportional to a ratio of a distance between the fulcrum point P 3-1 and the power point P 3-2 and a distance between the fulcrum point P 3-1 and the point of action P 3-3 .
- the thus reduced load is applied to the connecting portion 29 via the connecting portion 27 .
- the load applied to the connecting portion 29 is transferred to the load receiving portion 32 of the second load converting unit 30 by means of the bolt 38 . Therefore, the load receiving portion 32 of the second load converting unit 30 descends downward, while the parallelogram formed by the base portion 31 , load receiving portion 32 and parallel link portions 33 , 34 is maintained.
- the load applied to the load receiving portion 32 of the second load converting unit 30 is then transferred to the load receiving portion 52 of the load sensor unit, and is further transferred to the lever 55 via the connecting portion 53 .
- the load is reduced to a value proportional to a ratio of a distance between the fulcrum point P 4-1 and the power point P 4-2 and a distance between the fulcrum point P 4-1 and the point of action P 4-3 .
- the finally reduced load is applied to the tuning fork 58 as a pulling force and a frequency of the tuning fork 58 is changed. By detecting this frequency change of the tuning fork 58 , it is possible to measure the original load W, i.e. a weight of the article.
- the original load W is reduced by the first, second and third levers 14 , 19 and 24 of the first load converting unit 10 , and the thus reduced load is further reduced by the lever 55 of the load sensor unit 50 .
- the original load W is reduced by about 70 times.
- the first load converting unit 10 including the levers is arranged outside the Roberval mechanism 1 such that the levers 14 , 19 and 24 extend in a plane perpendicular to a plane in which the Roberval mechanism 1 extends, the weighing apparatus can be made small and compact, while the load applied to the load sensor, i.e. the tuning fork 58 can be reduced with a sufficient large ratio and a measurable range can be increased
- a load is applied to the load receiving portion 32 of the second load converting unit 30 and the load sensor unit 50 can be calibrated.
- the Roberval mechanism 1 , first and second load converting units 10 and 30 and load sensor unit 50 is provided within a housing. Since the standard weight is automatically placed on the weight placing box 40 by means of a driving motor, the calibration can be performed merely by operating a calibration button. It should be noted that the load is sufficiently reduced by the first load converting unit 10 , the standard weight having a small weight can be used.
- the Roberval mechanism 1 and first and second load converting units 10 , 30 and the load sensor unit 50 are formed by piercing the metal blocks and the metal plate, respectively.
- these members may be formed by composing a plurality of parts.
- the first load converting unit 10 includes the three levers 14 , 19 and 24 , but according to the invention, the load converting unit may have one or two or more than three levers.
- the load converting section is composed of the first and second load converting units 10 and 30 , but according to the invention, only the first load converting unit including at least one lever may be provided.
- the load sensor unit 50 may be provided on the first load converting unit 10 .
- the load sensor unit 50 includes the lever 55 , but the load sensor unit may not have any lever.
- the load is reduced by setting a distance between the fulcrum point and the power point smaller than a distance between the fulcrum point and the point of action. It should be noted that according to the invention, the load may be enlarged by suitably setting the above distances.
- the weighing apparatus by providing the load converting mechanism outside the Roberval mechanism, the load can be reduced or enlarged with a sufficiently large ratio without decreasing a mechanical strength of the Roberval mechanism. Therefore, the load sensor may be small and a measurable range can be increased.
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Abstract
Description
- Field of the Invention
- The present invention relates to a weighing apparatus comprising a Roberval mechanism including a base portion, a load receiving portion receiving a load to be measured and a pair of parallel link portions provided between the base portion and the load receiving portion via flexures, a load converting section including at least one lever having one end operationally coupled with said load receiving portion of the Roberval mechanism, and a load sensor operationally coupled with the other end of said lever, wherein the load applied to the load receiving portion of the Roberval mechanism is enlarged or reduced by the lever of the load converting section and a thus enlarged or reduced load is applied to the load sensor.
- Weighing apparatuses for measuring a weight of an article with a load cell unit including a Roberval mechanism, a load converting section and a load sensor have been disclosed in Japanese Patent Application Laid-open Publications Kokai Sho 63-277936 and Kokai Hei 1-240830.
- In these known weighing apparatuses, the load converting section including a lever for reducing a load to be applied to the load sensor is provided within the Roberval mechanism. However, in such weighing apparatuses, a freedom in designing the load converting section is limited. Furthermore, since the load converting section includes only one lever having a relatively small length, a sufficiently large ratio for enlarging or reducing a load could not be attained.
- In Japanese Patent Application Laid-open Publication Kokai 2000-283829, there is disclosed another known weighing apparatus with a Roberval mechanism, a load converting section and a load sensor, in which the load converting section is provided as a separate body from the Roberval mechanism such that a lever of the load converting section is extended in a plane which is parallel with a plane of the Roberval mechanism. In such a weighing apparatus, although a freedom of design of the load converting section is enhanced, a longitudinal dimension of the load converting section is liable to be large and a whole weighing apparatus could not be made small and compact. Moreover, although a length of the lever of the load converting section can be longer, it is impossible to provide a plurality of levers, and therefore a load enlarging or reducing ratio could not be made sufficiently large.
- The present invention has for object to provide a novel and useful weighing apparatus of a kind mentioned in the preamble, in which the above mentioned drawbacks of the known weighing apparatuses can be effectively removed by providing a load converting section as a separate unit from a Roberval mechanism, and a sufficiently high load enlarging or reducing ratio can be attained while the weighing apparatus can be small and compact.
- In order to attain the aforesaid object, a weighing apparatus for measuring a weight of an article comprising:
-
- a Roberval mechanisms having a base portion, a load receiving portion for receiving a load caused by an article to be measured and a pair of parallel link portions by means of which said base portion and load receiving portion are coupled with each other via flexures;
- a load converting section including at least one lever and arranged in a plane which is different from a plane in which said Roberval mechanism is arranged, one end of said lever being operationally coupled with said load receiving portion of the Roberval mechanism; and
- a load sensor unit including a load receiving portion which is operationally coupled with the other end of said lever of the load converting section, and a load sensor coupled with said load receiving portion of the load sensor unit, wherein the load applied to said load receiving portion of the Roberval mechanism is enlarged or reduced by the lever of the load converting section and a thus enlarged or reduced load is applied to the load sensor.
- In a preferable embodiment of the invention, said load converting section includes a first load converting unit having a plurality of levers coupled with each other in series, and a second load converting unit operationally coupled with the last lever of said first load converting unit, wherein said first load converting unit is provided in a plane perpendicular to the plane of the Roberval mechanism and said second load sensor is provided in a plane parallel to the plane of the Roberval mechanism. In such an embodiment, the second load converting unit may be formed as a Roberval mechanism and the load sensor unit may include a lever whose one end is operationally coupled with a load receiving portion of the Roberval mechanism of the second load converting unit, the other end of said lever of the load sensor unit being coupled with the load sensor.
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FIG. 1 is a perspective view showing an embodiment of the weighing apparatus according to the invention; -
FIG. 2 is an exploded perspective view of the weighing apparatus; -
FIG. 3 is a front view of a first load converting unit; -
FIG. 4 is a front view of a second load converting unit; and -
FIG. 5 is a front view showing a load sensor unit. - Now the present invention will be explained in detail with reference to embodiments shown in the accompanying drawings.
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FIG. 1 is a perspective view illustrating an embodiment of the weighing apparatus according to the present invention andFIG. 2 is an exploded perspective view thereof. The weighing apparatus comprises aRoberval mechanism 1 secured to a supportingmember 2. The Robervalmechanism 1 is manufactured by cutting a single metal block into a given configuration. The Robervalmechanism 1 includes abase portion 3, aload receiving portion 4, upper and lowerparallel link portions 5ad 6, and fourflexures 7, two of the four flexures being provided between thebase portion 3 and theparallel link portions load receiving portion 4 and theparallel link portions flexures 7 has formed therein a throughhole 8 such that an effective width of the flexure is narrowed. TheRoberval mechanism 1 further comprises afixing portion 3 a which extends from thebase portion 3 inwardly toward theload receiving portion 4. - To the
base portion 3 of theRoberval mechanism 1 is secured a firstload converting unit 10 such that the firstload converting unit 10 extends in a plane which is perpendicular to a plane in which the Robervalmechanism 1 extends. To the firstload converting unit 10 is secured a secondload converting unit 30 which extends in a plane which is perpendicular to the plane of the firstload converting unit 10 and is in parallel with the plane of theRoberval mechanism 1. To the secondload converting unit 30 is secured aload sensor unit 50 including a tuning-fork type vibrating element. - A
base portion 11 of the firstload converting unit 10 is secured to thefixing portion 3 a of the Roberval mechanism by means oflower bolts 9 a shown inFIG. 2 . The firstload converting unit 10 is formed by piercing a metal block to have a number of cut-out portions and several levers. The fixing portion of theRoberval mechanism 1 has formed therein a projection extending toward theload receiving portion 4 and the above mentionedbolts 9 a are secured to this projection. - The first
load converting unit 10 includes aload receiving portion 12 which is coupled with theload receiving portion 4 of theRoberval mechanism 1 by means ofupper bolts 9 b shown inFIG. 2 . To this end, theload receiving portion 4 of theRoberval mechanism 1 includes aprojection 4 a extending toward thefixing portion 3 a and through holes. Screw holes are formed on a top surface of theload receiving portion 12 of the firstload converting unit 10 and thebolts 9 b are screwed into these screw holes through the through holes formed in theprojection 4 a to couple theload receiving portion 12 of the firstload converting unit 10 to theload converting portion 4 of theRoberval mechanism 1. As illustrated inFIG. 3 , the firstload converting unit 10 further includes afirst lever 14 whose one end is coupled with thebase portion 11 via aflexure 13 serving as a fulcrum point P1-1. A middle portion of thefirst lever 14 is coupled with theload receiving portion 12 via a connectingportion 15 such that said middle portion serves as a power point P1-2. The other end of thefirst lever 14 serving as a point of action P1-3 is coupled with one end of asecond lever 19 by means of aflexure 16, a connectingportion 17 and aflexure 18. This end of thesecond lever 19 serves as a power point P2-2. Thesecond lever 19 is supported by thebase portion 11 by means of a flexure 20 serving as a fulcrum point P21-. The other end of thesecond lever 19 is coupled with an upper end of a vertically extending connectingportion 22 via aflexure 21 serving as a point of action P2-3. - A lower end of the connecting
portion 22 is coupled with one end of athird lever 24 by means of aflexure 23 serving as a power point P3-2. Thethird lever 24 is connected to thebase portion 11 via aflexure 25 serving as a fulcrum point P3-1, and the other end of thethird lever 24 is coupled with a substantially circular connecting portion via aflexure 26 serving as a point of action P3-3, a connectingportion 27 and aflexure 28. - It should be noted that the
base portion 11,load receiving portion 12, first tothird levers load converting unit 10 is formed, but some of theflexures -
FIG. 4 is a front view showing the secondload converting unit 30. The secondload converting unit 30 is also formed by piecing a single metal block to constitute a Roberval mechanism including abase portion 31, aload receiving portion 32,parallel link portions flexures 35. As illustrated inFIG. 2 , each of theflexures 36 has formed therein a throughhole 36 to reduce its effective thickness. - The
base portion 31 of the secondload converting unit 30 is secured to a side wall of thefitting portion 3 a of theRoberval mechanism 1 by means ofbolts 37 and aseat 3 b secured to the side wall of thefitting portion 3 a and having formed therein screw holes. On a front wall of theload receiving portion 32 of the secondload converting unit 30, is provided aseat 32 a having a screw hole formed therein, and the connectingportion 29 of the firstload converting unit 10 is secured to theseat 32 a by means of abolt 38. The secondload converting unit 30 further comprises asensor fitting portion 31 a to extend from thebase portion 31 toward theload receiving portion 32 in a space formed between the upper and lowerparallel link portions sensor fitting portion 31 a; there are secured aseat 31 b having a screw hole formed therein and ascrew hole 31 c into which a positioning pin 62 is screwed for positioning thesensor unit 50. On a side wall of theload receiving portion 32 of the secondload converting unit 30, is secured aseat 32 b having a screw hole formed therein for securing a load receiving portion of theload sensor unit 50 as will be explained later. Furthermore, to theload receiving portion 32 of the secondload converting unit 30 is secured aweight receiving box 40 by means ofbolts 41. -
FIG. 5 is a front view of theload sensor unit 50. Theload sensor unit 50 is formed by piecing a relatively thin metal plate. Theload sensor unit 50 includes abase portion 51 and aload receiving portion 52. Thebase portion 51 is secured to thesensor fitting portion 31 a of the secondload converting unit 30 by screwing abolt 60 into the screw hole formed in theseat 31 b, and theload receiving portion 52 is secured to theload receiving portion 32 of the secondload converting unit 30 by screwing abolt 61 into the screw hole formed in theseat 32 b. Thebase portion 51 of theload sensor unit 50 has formed therein a cut-outportion 51 b through which the positioning pin 62 extends from the side wall of thesensor fitting portion 31 a of the secondload converting unit 30 to position theload sensor unit 50. - The
load receiving portion 52 of theload sensor unit 50 is coupled with one end of alever 55 by means of connectingportion 53 and aflexure 54 which serves as a power point P4-2. Thelever 55 is supported by thebase portion 51 by means of aflexure 56 serving as a fulcrum point P4-1, and the other end of thelever 55 is coupled with an upper end of atuning fork 58 via aflexure 57 serving as a point of action P4-3. A lower end of thetuning fork 58 is coupled with thebase portion 51 by means of aflexure 59. - In the
base portion 51 of theload sensor unit 50 there is formed a throughhole 51 a through which thebolt 60 passes, and in theload receiving portion 52 of theload sensor unit 50 there is formed a throughhole 52 a through which thebolt 61 passes. - Upon measuring a weight of an article, the article is placed on an article receiving pan (not shown in the drawings) secured to the
load receiving portion 4 of theRoberval mechanism 1, and then a load W is applied to theload receiving portion 4 and the load receiving portion descends. Since theload receiving portion 4 is constructed in theRoberval mechanism 1, even though theload receiving portion 4 moves downward, the parallelogram formed by thebase portion 3, load receivingportion 4 andparallel link portions - The load W applied to the
load receiving portion 4 of theRoberval mechanism 1 is transferred to theload receiving portion 12 of the firstload converting unit 10 and is further transferred to the power point P1-2 of thefirst lever 14. The load W is reduced to a value which is proportional to a ratio of a distance D1 between the fulcrum point P1-1, and the power point P1-2 and a distance D2 between the fulcrum point P1-2 and the point of action P1-3. In the present embodiment, the distance D2 is longer than the distance D1 by about three times, and therefore the load W is reduced to a third thereof. The thus reduced load is transferred to the power point P2-2 of thesecond lever 19 via the connectingportion 17. The load is further reduced by thelever 19 to a value proportional to a ratio of a distance between the fulcrum point P2-1 and the power point P2-2 and a distance between the fulcrum point P2-1 and the point of action P2-3. The reduced load is further transferred via the connectingportion 22 to thethird lever 24. In thethird lever 24, the load is further reduced to a value which is proportional to a ratio of a distance between the fulcrum point P3-1 and the power point P3-2 and a distance between the fulcrum point P3-1 and the point of action P3-3. The thus reduced load is applied to the connectingportion 29 via the connectingportion 27. - The load applied to the connecting
portion 29 is transferred to theload receiving portion 32 of the secondload converting unit 30 by means of thebolt 38. Therefore, theload receiving portion 32 of the secondload converting unit 30 descends downward, while the parallelogram formed by thebase portion 31,load receiving portion 32 andparallel link portions - The load applied to the
load receiving portion 32 of the secondload converting unit 30 is then transferred to theload receiving portion 52 of the load sensor unit, and is further transferred to thelever 55 via the connectingportion 53. In thelever 55, the load is reduced to a value proportional to a ratio of a distance between the fulcrum point P4-1 and the power point P4-2 and a distance between the fulcrum point P4-1 and the point of action P4-3. Then the finally reduced load is applied to thetuning fork 58 as a pulling force and a frequency of thetuning fork 58 is changed. By detecting this frequency change of thetuning fork 58, it is possible to measure the original load W, i.e. a weight of the article. - In this manner, the original load W is reduced by the first, second and
third levers load converting unit 10, and the thus reduced load is further reduced by thelever 55 of theload sensor unit 50. In the present embodiment, the original load W is reduced by about 70 times. According to the invention, since the firstload converting unit 10 including the levers is arranged outside theRoberval mechanism 1 such that thelevers Roberval mechanism 1 extends, the weighing apparatus can be made small and compact, while the load applied to the load sensor, i.e. thetuning fork 58 can be reduced with a sufficient large ratio and a measurable range can be increased - In the present embodiment, by placing a standard weight on the
weight placing box 40, a load is applied to theload receiving portion 32 of the secondload converting unit 30 and theload sensor unit 50 can be calibrated. TheRoberval mechanism 1, first and secondload converting units load sensor unit 50 is provided within a housing. Since the standard weight is automatically placed on theweight placing box 40 by means of a driving motor, the calibration can be performed merely by operating a calibration button. It should be noted that the load is sufficiently reduced by the firstload converting unit 10, the standard weight having a small weight can be used. - In the above embodiment, the
Roberval mechanism 1 and first and secondload converting units load sensor unit 50 are formed by piercing the metal blocks and the metal plate, respectively. However, according to the invention, these members may be formed by composing a plurality of parts. - Moreover, in the above embodiment, the first
load converting unit 10 includes the threelevers load converting units load sensor unit 50 may be provided on the firstload converting unit 10. In the above embodiment, theload sensor unit 50 includes thelever 55, but the load sensor unit may not have any lever. - In the above embodiment, the load is reduced by setting a distance between the fulcrum point and the power point smaller than a distance between the fulcrum point and the point of action. It should be noted that according to the invention, the load may be enlarged by suitably setting the above distances.
- As explained above, the weighing apparatus according to this invention, by providing the load converting mechanism outside the Roberval mechanism, the load can be reduced or enlarged with a sufficiently large ratio without decreasing a mechanical strength of the Roberval mechanism. Therefore, the load sensor may be small and a measurable range can be increased.
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Application Number | Priority Date | Filing Date | Title |
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US10/875,370 US7091428B2 (en) | 2004-06-24 | 2004-06-24 | Weighing apparatus with Roberval mechanism |
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US10/875,370 US7091428B2 (en) | 2004-06-24 | 2004-06-24 | Weighing apparatus with Roberval mechanism |
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US20050284670A1 true US20050284670A1 (en) | 2005-12-29 |
US7091428B2 US7091428B2 (en) | 2006-08-15 |
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US (1) | US7091428B2 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US20120073387A1 (en) * | 2009-06-30 | 2012-03-29 | Shinko Denshi Co., Ltd. | Load detection sensor |
US20170356789A1 (en) * | 2016-06-10 | 2017-12-14 | Jensen Usa Inc. | Weighing Apparatus |
JP2020159775A (en) * | 2019-03-25 | 2020-10-01 | 新光電子株式会社 | Load sensor equipped with tuning-fork oscillator |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102006031950B3 (en) * | 2006-07-11 | 2007-11-22 | Sartorius Ag | Top-pan balance for weighing goods, has scale pan fastenable on top side of edge load sensor, where edge load sensor is connected with stationary correction electronic system e.g. personal computer, by wireless connection |
CN102317744B (en) * | 2009-02-10 | 2013-09-04 | 株式会社岛津制作所 | Sensor mechanism body and electronic balance using the same |
US11698309B2 (en) * | 2020-03-05 | 2023-07-11 | Delta Electronics, Inc. | Linear actuator |
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US5866854A (en) * | 1996-02-12 | 1999-02-02 | Mettler-Toledo Ag | Calibrating device for a balance |
US6194672B1 (en) * | 1998-05-08 | 2001-02-27 | Mettler-Toledo Gmbh | Balance with a mechanical coupling area for a calibration weight |
US6307165B1 (en) * | 1998-11-30 | 2001-10-23 | Shimadzu Corporation | Electronic balance |
US6563060B2 (en) * | 2000-05-31 | 2003-05-13 | Shimadzu Corporation | Electronic balance |
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JPH0629761B2 (en) | 1987-05-09 | 1994-04-20 | 株式会社島津製作所 | Electronic balance |
JPH0776713B2 (en) | 1988-03-22 | 1995-08-16 | 株式会社島津製作所 | Electronic balance |
JP3818415B2 (en) | 1999-03-30 | 2006-09-06 | 株式会社エー・アンド・デイ | Electromagnetic balance type electronic balance |
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US5866854A (en) * | 1996-02-12 | 1999-02-02 | Mettler-Toledo Ag | Calibrating device for a balance |
US6194672B1 (en) * | 1998-05-08 | 2001-02-27 | Mettler-Toledo Gmbh | Balance with a mechanical coupling area for a calibration weight |
US6307165B1 (en) * | 1998-11-30 | 2001-10-23 | Shimadzu Corporation | Electronic balance |
US6563060B2 (en) * | 2000-05-31 | 2003-05-13 | Shimadzu Corporation | Electronic balance |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120073387A1 (en) * | 2009-06-30 | 2012-03-29 | Shinko Denshi Co., Ltd. | Load detection sensor |
EP2450685A1 (en) * | 2009-06-30 | 2012-05-09 | Shinko Denshi Company Limited | Load detection sensor |
EP2450685A4 (en) * | 2009-06-30 | 2012-12-19 | Shinko Denshi Kk | Load detection sensor |
US8770044B2 (en) * | 2009-06-30 | 2014-07-08 | Shinko Denshi Co., Ltd. | Load detection sensor |
US20170356789A1 (en) * | 2016-06-10 | 2017-12-14 | Jensen Usa Inc. | Weighing Apparatus |
US10175090B2 (en) * | 2016-06-10 | 2019-01-08 | Jensen Usa Inc. | Weighting apparatus incorporating a freely supported container |
JP2020159775A (en) * | 2019-03-25 | 2020-10-01 | 新光電子株式会社 | Load sensor equipped with tuning-fork oscillator |
JP7267799B2 (en) | 2019-03-25 | 2023-05-02 | 新光電子株式会社 | Load sensor with tuning fork oscillator |
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